<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    #app1,
    #app2 {
      border: 1px solid #000;
    }
  </style>
</head>

<body>
  <div id="app1">
    实例1
  </div>

  <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.7.9/vue.js"></script>
  <script>
    const app1 = new Vue({
      el: "#app1",
      data: {
        arr: [1, 2, 3, 4]
      }
    })

    console.log(app1.arr.push === Array.prototype.push)




  </script>
</body>

</html>